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Two balls are projected simultaneously w...

Two balls are projected simultaneously with the same speed from the top of a tower, one vertically upwards and the other vertically downwards. They reach the ground in 9 second and 4 second respectively. The height of the tower is:

A

100 m

B

120 m

C

180 m

D

200 m

Text Solution

Verified by Experts

The correct Answer is:
c
Here `h=9(-v)+(1)/(2)xx10xx81`
`= -9v+405`
Also `h=4v+(1)/(2)xx10xx64`
`=4v+320`
Subtracting 13v =325 or v=25 m `s^(-1)`
Thus putting in (i) h=180 m.
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